Nitroglycerin inhibits the development of morphine tolerance and dependence in rats

The development of tolerance to and physical dependence on opioids remains a significant barrier to their clinical use. N-Methyl-D-aspartate (NMDA) receptor antagonists inhibit tolerance and dependence. However, many NMDA antagonists have undesirable side effects. It has been shown that nitroglycerin (NTG) can antagonize NMDA receptor activity. This study was designed to determine whether NTG could inhibit the development of morphine tolerance and dependence. Rats were anesthetized and implanted with either morphine or placebo pellets, and pumps infusing vehicle or NTG (doses from 0.1 microg/kg/day to 10 mg/kg/day). Tolerance development was assessed by tail-flick latency (TFL). After 6 days, withdrawal was precipitated by subcutaneous injection of 2 mg/kg naloxone. Withdrawal signs were observed for 15 min. Placebo-pelleted rats showed no changes in TFL over the course of the study and no withdrawal signs. Morphine-pelleted rats developed tolerance. The 0.1 mg/kg/day NTG dose significantly attenuated tolerance development, while the other doses had no significant effect. The 0.1 mg/kg/day dose also attenuated some withdrawal signs. Higher or lower doses were not effective, possibly because of competing biochemical effects.     

Role of catecholaminergic mechanisms in the expression of the morphine abstinence syndrome in rats

The effect of various drugs affecting catecholaminergic mechanisms on the precipitated morphine withdrawal syndrome was studied in rats which had developed a medium degree of dependence. Administration of low doses of d-amphetamine, cocaine, and L-Dopa shortly before precipitating withdrawal by levallorphan induced a dose-dependent increase of dominant withdrawal signs such as jumping and a decrease of recessive signs such as wet dog shaking; signs such as diarrhea and ptosis decreased, whereas rhinorrhea, salivation and lacrimation increased. A qualitatively very similar change in withdrawal signs occurred when withdrawal was precipitated in extremely highly dependent rats and/or increasing doses of the antagonist were administered. Therefore, the effects of the above drugs are interpreted as potentiation of withdrawal. Pretreatment with higher doses of the same drugs provoked strong stereotyped behaviour which obviously suppressed the occurrence of other motor signs.Activation of noradrenergic or dopaminergic mechanisms with desipramine or apomorphine induced an increase in the intensity of withdrawal, which was, however, much more pronounced after the former than the latter drug. When catecholamines (CA) were previously depleted by alpha-methyl-para-tyrosine (AMT), apomorphine lost a great part of its effectiveness. Blockade of CA synthesis by AMT alone resulted in decreased jumping while at the same time writhing largely increased, thus, inducing a profile of signs characteristic for a weak withdrawal. Selective inhibition of noradrenaline synthesis by FLA-63 resulted in a reduction in withdrawal intensity. Ro 4-4602 + L-Dopa, given after AMT, antagonized and reversed the reduction of withdrawal, but this effect was not so pronounced when by additional pretreatment with FLA-63 NA levels remained low. It is concluded that of both brain CA especially noradrenaline is involved in the manifestation of the morphine withdrawal syndrome.     

Protective effect of Matricaria chamomilla on ethanol-induced acute gastric mucosal injury in rats

The antiulcerogenic and antioxidant properties of Matricaria chamomilla L. (Compositae) hydroalcoholic extract (MCE) on ethanol-induced gastric mucosal injury were investigated in rats. After the induction of gastric mucosal injury, all groups were sacrificed; the gastric ulcer index was calculated, and malondialdehyde (MDA) and reduced glutathione (GSH) in whole blood and gastric tissue, and serum ascorbic acid, retinol, and β-carotene levels were measured in all groups. Pretreatment with MCE at some doses significantly reduced gastric lesions. Again, some doses of MCE significantly reduced the MDA, and significantly increased GSH levels in gastric tissue or whole blood. Serum β-carotene and retinol levels were significantly higher in the 200?mg/kg MCE-administered group with respect to control. As a result, MCE clearly has a protective effect against ethanol-induced gastric mucosal lesions, and this effect, at least in part, depends upon the reduction in lipid peroxidation and augmentation in antioxidant activity.     

The role of central serotoninergic neurotransmission in the morphine abstinence syndrome in rats

It was found that 200 mg/kg of DL-p-chlorophenylalanine (PCPA) and 2 mg/kg of methergoline drugs inhibiting central serotoninergic transmission-decreased naloxone precipitated abstinence wet dog shakes in morphine-dependent rats. The inhibitory effect of PCPA was reversed by 200 mg/kg of 5-hydroxy-L-tryptophan (5-HTP) but not by the same amount of L-tryptophan (TP). 5-HTP alone (200 mg/kg) increased wet dog shakes epissodes, whereas TP alone in the same dosage practically did not have any influence on the wet dog shakes in morphine-dependent rats. These findings suggest that brain serotonin may play some role in the expression of wet dog shakes in morphine-dependent rats.     

Butorphanol precipitates abstinence in morphine dependent rats

Butorphanol precipitated a withdrawal syndrome in rats receiving continuous intracerebroventricular infusions of morphine for three days. However, the potency of butorphanol to induce defecation, urination, teeth chattering and escape behavior was one to two orders of magnitude less on a molar basis than that of naloxone. Wet shake behavior, a prominent feature of naloxone precipitated withdrawal, was absent in morphine dependent animals challenged with butorphanol. These data indicate qualitative as well as quantitative differences in the withdrawal syndromes induced by butorphanol and naloxone.     

Physiological responses of Matricaria chamomilla to cadmium and copper excess

Physiological responses of Matricaria chamomilla plants exposed to cadmium (Cd) and copper (Cu) excess (3, 60, and 120 microM for 7 days) with special emphasis on phenolic metabolism were studied. Cu at 120 microM reduced chamomile growth, especially in the roots where it was more abundant than Cd. Notwithstanding the low leaf Cu amount (37.5 microg g(-1) DW) in comparison with Cd (237.8 microg g(-1) DW) at 120 microM, it caused reduction of biomass accumulation, F(v)/F(m) ratio and soluble proteins. In combination with high accumulation of phenolics, strong reduction of proteins and high GPX activity in the roots, this supports severe redox Cu properties. In terms of leaf phenylalanine ammonia-lyase (PAL) activity, it seems that Cd had a stimulatory effect during the course of the experiment, whereas Cu was found to stimulate it after 7-day exposure. The opposite trend was visible in the roots, where Cd had a stimulatory effect at high doses but Cu mainly at the highest dose. This supports the assumption of different PAL time dynamics under Cd and Cu excess. A dose of 60 and 120 microM Cu led to 2- and 3-times higher root lignin accumulation while the same Cd doses increased it by 33 and 68%, respectively. A Cu dose of 120 microM can be considered as limiting for chamomile growth under conditions of present research, while resistance to high Cd doses was confirmed. However, PAL and phenolics seemed to play an important role in detoxification of Cd- and Cu-induced oxidative stress.     

Changes in fixed-interval behavior during chronic morphine treatment and morphine abstinence in rats

Rats previously trained to a fixed-interval schedule (FI 2 min) were treated twice daily with saline or morphine hydrochloride (final dose 40 mg/kg i.p.) for 44 days.On day 45 an abstinence state was induced by withdrawing morphine or by giving nalorphine (1 mg/kg i.p.). Operant behavior was recorded on alternate days during the period of chronic treatment and during the withdrawal phase (21 days). It was found that the number of lever presses decreased significantly during the first days of morphine administration but increased later over the control values. The quarter-life was not changed during this period. Morphine withdrawal and nalorphine treatment both caused a further increase in lever presses that lasted about 11 days. Again quarter-life was not changed. These results indicate that the effects of morphine on FI behavior in rats not only undergo tolerance but are actually reversed during the chronic treatment.The data obtained during the withdrawal phase are discussed in relation to the secondary abstinence syndrome described by Martin et al. (1963).     

The role of GABA in morphine abstinence in rats

GABA mimetics such as baclofen, aminooxyacetic acid (AOAA) and diazepam decreased naloxone-precipitated abstinence wet dog shakes in morphine dependent rats. The GABA antagonists bicuculline and picrotoxin were not effective in small doses. The inhibition of wet dog shakes by baclofen, AOAA and diazepam was not reversed by bicuculline. This suggests that baclofen, AOAA and diazepam may inhibit morphine wet dog shakes not by direct GABA receptor stimulation. Inhibition by baclofen of wet dog shakes was reversed by 5-hydroxytryptophan (5-HTP) suggesting that the inhibiting effects of GABA mimetics are mediated by serotoninergic neurons.     

Isolation of Herniarin and Other Constituents from Matricaria chamomilla Flowers

Matricaria chamomilla L. (Asteraceae) flowers on hydrodistillation yielded an essential oil and on extraction with organic solvents afforded a biologically active coumarin, herniarin (1). The extracts also yielded oleanolic acid (2), stigmasterol (3), ß-sitosterol (4) and its glucoside (5), of which 2, 4 and 5 are being reported for the first time from M. chamomilla. Complete spectral data of herniarin (1) are reported.     

Opiate-like action of methionine-enkephalin in inhibiting morphine abstinence syndrome

Intracerebroventricular administration of methionine-enkephalin or morphine sulfate immediately prior to naloxone administration inhibited the precipitated withdrawal jumping response in mice rendered dependent on morphine by the pellet implantation method. Both methionine-enkephalin and morphine sulfate failed to inhibit withdrawal defecation and rearing behavior. Morphine sulfate was found to be four times as potent as methionine-enkephalin, on molar basis, in inhibiting the abstinence syndrome. These data provide new in vivo pharmacologic evidence for the opiate-like action of methionine-enkephalin.     

Role of ploidy in cadmium and nickel uptake by Matricaria chamomilla plants

Cadmium and nickel uptake by diploid and tetraploid chamomile (Matricaria chamomilla L.) cultivars (Novbona and Lutea, respectively) exposed to 60 μM solutions of individual metals over 7 days was studied. Diploid plants accumulated higher amount of Cd in both shoots and roots compared to tetraploid plants while Ni accumulation was ploidy-independent. Cd presence caused higher accumulation of total soluble phenols and flavonoids and higher phenylalanine ammonia-lyase and guaiacol-peroxidase activities in diploid cultivar in comparison with tetraploid but phenolic acids did not show direct correlation with metal accumulation and even decreased in the leaves of Ni-exposed plants. Lignin content was preferentially elevated in the roots of diploid cultivar. Among 17 free amino acids, their sum increased mainly in the leaves of Cd-exposed plants (owing to increase in serine, alanine and proline). Potassium decrease in both cultivars in response to Cd was ploidy-independent and Ca, Mg and Fe accumulation were almost unaffected. It is concluded that Cd accumulation in chamomile may be mediated by the accumulation of phenols but they have no active role in shoot Ni accumulation. Present findings in the context of our previous studies and limited available literature about ploidy effect on metal accumulation are discussed.     

Ionotropic glutamatergic neurotransmission in the ventral tegmental area modulates DeltaFosB expression in the nucleus accumbens and abstinence syndrome in morphine withdrawal rats

The present study sought to assess whether the blockade of ionotropic glutamate receptors in the ventral tegmental area could modulate morphine withdrawal in morphine-dependent rats and the expression of stable DeltaFosB isoforms in the nucleus accumbens during morphine withdrawal. Rats were injected (i.p.) with increasing doses of morphine for 1 week to develop physical dependence, and withdrawal was then precipitated by one injection of naloxone (2 mg/kg, i.p.). Abstinence signs such as jumping, wet-dog shake, writhing posture, weight loss, and Gellert-Holtzman scale score were recorded to evaluate naloxone-induced morphine withdrawal. Two ionotropic glutamate receptor antagonists, dizocilpine (MK-801) and 6, 7-dinitroquinnoxaline-2, 3-dione (DNQX), were microinjected unilaterally into the ventral tegmental area 30 min before naloxone precipitation. A second injection of naloxone (2 mg/kg i.p.) was given 1 h after the first naloxone injection to sustain a maximal level of withdrawal so that the expression of stable DeltaFosB isoforms in the nucleus accumbens could be measured. This would enable determination of the correlation between the MK-801 or DNQX-induced decrease in somatic withdrawal signs and the change in neuronal activity in the nucleus accumbens. The results showed that both MK-801 and DNQX significantly alleviated all symptoms of morphine withdrawal except for weight loss and reduced the expression of stable DeltaFosB isoforms within the nucleus accumbens. These data suggest that ionotropic glutamatergic neurotransmission in the ventral tegmental area regulates the levels of stable DeltaFosB isoforms in the nucleus accumbens, which play a very important role in modulating opiate withdrawal.     

Dynamics of Coumarin Production in Leaves of Diploid and Tetraploid Matricaria chamomilla.

ABSTRACT

The content of herniarin, (Z.)- and (E.)-2-β.-D-glucopyranosyloxy-4-methoxycinnamic acid, umbelliferone, chlorogenic acid, and (Z.)- and (E.)-ene-yne-dicycloether was evaluated in Matricaria chamomilla.L. leaf rosette in relation to the leaf age. Developmental changes of the herniarin quantity in diploid and tetraploid cultivar were similar. The highest content of (E.)-2-β.-D-glucopyranosyloxy-4-methoxycinnamic acid was found in the youngest leaves. The amount of umbelliferone and chlorogenic acid increased with the leaf age. Differences in amount of (Z.)- and (E.)-ene-yne-dicycloether between tetraploid and diploid plants were significant in all leaf pairs. However, their content during the leaf development was not considerably changed, contrary to coumarins.     

Salicylic acid alleviates NaCl-induced changes in the metabolism of Matricaria chamomilla plants

Influence of 100 mM NaCl and 50 μM salicylic acid (SA) and their combination on the metabolism of chamomile (Matricaria chamomilla) during 7 days was studied. NaCl reduced growth and selected physiological parameters and SA in combined treatment (NaCl + SA) reversed majority of these symptoms. Application of SA reduced NaCl-induced increase of Na⁺ in the rosettes, but not in the roots. Accumulation of total amino acids was stimulated in NaCl-treated roots, especially due to exceptional increase of proline (4.4-fold). Among phenolic acids, accumulation of protocatechuic acid was the most enhanced in NaCl-exposed leaf rosettes (ca. 3-fold) while chlorogenic and caffeic acids in the roots (2.4- and 2.8-fold, respectively). Total soluble phenols increased after NaCl and SA treatments, but root lignin content was not affected. Activity of phenylalanine ammonia-lyase and shikimate dehydrogenase increased in response to NaCl, but cinnamyl alcohol dehydrogenase was not affected and polyphenol oxidase decreased. Stress parameters were elevated by NaCl treatment (superoxide radical and malondialdehyde content, activities of catalase, ascorbate- and guaiacol-peroxidase) and substantially prevented by SA, while accumulation of hydrogen peroxide decreased. Overall, SA showed strong beneficial properties against NaCl-induced negative symptoms. Protective effect of SA was the most visible at the level of guaiacol-peroxidase and through amelioration of stress parameters and mineral nutrient contents.     

Weight loss and shock-elicited aggression as indices of morphine abstinence in rats

Weight loss and shock-elicited aggression have been compared as quantitative indices of morphine abstinence in rats. A range of doses of morphine was administered to rats by i.p. injection twice daily for 12–15 days. After injections were stopped, morphine-abstinent rats lost weight precipitously, and showed an increased frequency of fighting in response to aversive stimulation (foot-shock). Recovery of weight appeared complete after 15–20 days but a significant increase in aggression was found at 18 days post-withdrawal; this virtually disappeared after 52 days. Both the amount of weight lost and the frequency of fighting increased as a function of the previous maintenance dose of morphine; the effective dose range appeared similar for these two indices. Weight loss was much less variable than fighting, had the advantage of rapid, objective measurement, and appeared to be the more reliable index of abstinence.